Effectiveness of exercise for osteoarthritis of the knee: A review of the literature

Abstract

Osteoarthritis (OA) of the knee is the most common type of arthritis and the major cause of chronic musculoskeletal pain and mobility disability in the elderly. The objective of this paper is to discuss the effectiveness of exercise for OA of the knee based on a review of the literature. We reviewed the relevant literature, i.e. systematic reviews and meta-analyses searched using PubMed. Muscle strengthening and aerobic exercises are effective in reducing pain and improving physical function in patients with mild to moderate OA of the knee.

Keywords: Hamstrings; Muscle strengthening exercise; Osteoarthritis of the knee; Quadriceps.

Figure 1

Medx knee machine (Back In Action, CA, USA). The strength of the knee extensor and flexor muscles was measured with a Medx knee machine. Each patient underwent isokinetic and isometric testing of the knee extensor and flexor muscles. Patients were positioned on the Medx knee machine chair with stabilization supports across the pelvis and distally over the thighs. Patients gripped the side of the chair and leaned back against the backrest which was inclined posteriorly to an angle of 90° above horizontal. The isometric torques of the both knee extensor and flexor muscles were measured with the both legs together at 6 points between 0° and 120° and then the maximum peak torque values of the knee extensor and flexor muscles were evaluated.

Figure 2

Effect of exercise on maximum peak torque of the knee extensor and flexor muscles[28]. The muscle strength test was performed at baseline and then at between 6 and 12 mo (mean: 229 d) after the start of the exercise regimen. The MPT of the knee extensor and flexor muscles significantly increased by 42.5% and 60.4% respectively in all the patients.

Figure 3

Longitudinal percent changes in the maximum peak torque values of the knee extensor and flexor muscles over 5 years[32]. Data are expressed as mean ± SD. Data comparison between baseline and time point was performed by unpaired t-test. All of the patients (n = 26) were able to complete the exercise program at 3-6 mo. Twenty-four (92.3%) and 17 (65.3%) patients were able to complete the exercise program at 1-3 years and 5 years respectively after the start of the exercise regimen. The beneficial effect of the exercises on the maximum peak torque values was observed in 3-6 mo after the start of the exercise regimen and maintained up to 1-3 years. The effect of the exercises was greater in the knee extensor muscle than in the knee flexor muscle. However, the beneficial effect of the exercises tended to be lost 5 years after the start of the exercise regimen. NS: Not significant.